Revert "Kernel: Move Singleton class to AK"

This reverts commit f0906250a181c831508a45434b9f645ff98f33e4.

2 files changed, 4 insertions, 131 deletions

diff --git a/AK/FlyString.cpp b/AK/FlyString.cpp
index e6e369c3f6..fdf2eed56a 100644
--- a/AK/FlyString.cpp
+++ b/AK/FlyString.cpp
@@ -27,7 +27,6 @@
 #include <AK/FlyString.h>
 #include <AK/HashTable.h>
 #include <AK/Optional.h>
-#include <AK/Singleton.h>
 #include <AK/String.h>
 #include <AK/StringUtils.h>
 #include <AK/StringView.h>
@@ -48,11 +47,12 @@ struct FlyStringImplTraits : public AK::Traits<StringImpl*> {
     }
 };
 
-static auto s_table = make_singleton<HashTable<StringImpl*, FlyStringImplTraits>>();
-
 static HashTable<StringImpl*, FlyStringImplTraits>& fly_impls()
 {
-    return *s_table;
+    static HashTable<StringImpl*, FlyStringImplTraits>* table;
+    if (!table)
+        table = new HashTable<StringImpl*, FlyStringImplTraits>;
+    return *table;
 }
 
 void FlyString::did_destroy_impl(Badge<StringImpl>, StringImpl& impl)
diff --git a/AK/Singleton.h b/AK/Singleton.h
deleted file mode 100644
index 57962e3176..0000000000
--- a/AK/Singleton.h
+++ /dev/null
@@ -1,127 +0,0 @@
-/*
- * Copyright (c) 2020, the SerenityOS developers.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- *    list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#pragma once
-
-#include <AK/Assertions.h>
-#include <AK/Atomic.h>
-#include <AK/kmalloc.h>
-#ifdef KERNEL
-#include <Kernel/Arch/i386/CPU.h>
-#endif
-
-#ifndef __serenity__
-#    include <new>
-#endif
-
-namespace AK {
-
-template<typename T, T* (*InitFunction)()>
-class Singleton {
-    AK_MAKE_NONCOPYABLE(Singleton);
-public:
-    Singleton() = default;
-
-    T* ptr() const
-    {
-        T* obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
-        if (FlatPtr(obj) <= 0x1) {
-            // If this is the first time, see if we get to initialize it
-#ifdef KERNEL
-            Kernel::ScopedCritical critical;
-#endif
-            if (obj == nullptr && AK::atomic_compare_exchange_strong(&m_obj, obj, (T*)0x1, AK::memory_order_acq_rel)) {
-                // We're the first one
-                obj = InitFunction();
-                AK::atomic_store(&m_obj, obj, AK::memory_order_release);
-            } else {
-                // Someone else was faster, wait until they're done
-                while (obj == (T*)0x1) {
-#ifdef KERNEL
-                    Kernel::Processor::wait_check();
-#else
-                    // TODO: yield
-#endif
-                    obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
-                }
-            }
-            // We should always return an instance
-            ASSERT(obj != nullptr);
-            ASSERT(obj != (T*)0x1);
-        }
-        return obj;
-    }
-
-    T* operator->() const
-    {
-        return ptr();
-    }
-
-    T& operator*() const
-    {
-        return *ptr();
-    }
-
-    operator T*() const
-    {
-        return ptr();
-    }
-
-    operator T&() const
-    {
-        return *ptr();
-    }
-
-    bool is_initialized() const
-    {
-        T* obj = AK::atomic_load(&m_obj, AK::memory_order_consume);
-        return FlatPtr(obj) > 0x1;
-    }
-
-    void ensure_instance()
-    {
-        (void)ptr();
-    }
-
-private:
-    mutable T* m_obj { nullptr }; // atomic
-};
-
-template<typename T>
-struct SingletonInstanceCreator {
-    static T* create()
-    {
-        return new T();
-    }
-};
-
-template<typename T>
-inline Singleton<T, SingletonInstanceCreator<T>::create> make_singleton()
-{
-    return Singleton<T, SingletonInstanceCreator<T>::create>();
-}
-
-}